Designers of electronic equipment have become increasingly challenged to provide high-power devices in relatively small packages. These devices require compact and highly efficient cooling systems. A typical cooling system involves moving air across one or more printed circuit boards. The flow path layout, type of air moving device, and how well it is integrated into the system are all key elements in achieving the desired performance in a small package size with limited noise.
One such electronic device is a telecommunications router which typically includes a series of electronics communications “cards” arrayed with cooling fans in a chassis. The desire to make routers more powerful, yet compact in size, leaves little space for cooling system components necessary to address ever-increasing heat loads. Conventional system designs often employ fans that are not well matched to the system pressures, or do not move air efficiently within the space constraints, and result in unacceptable noise and relatively large power consumption.
Design efforts to date typically use multiple axial fans arranged in a “tray”, as illustrated in FIG. 1. The fans either push cooling air through a chassis or pull warm air out from the chassis. Higher fan speeds have been used to address increased flow requirements, but as system pressures increase, designers have responded by adding additional trays of axial fans arranged in series. An example of such series of axial fan trays is illustrated in FIG. 2. In theory, each axial fan tray handles half of the system pressure. The conventional arrangement illustrated in FIG. 2 sets forth an orientation with both fan trays downstream from the electronics being cooled in the electronics chassis, thereby pulling cooling air through the system. In other conventional arrangements, fan trays may be disposed upstream of the electronics being cooled, or fan trays being disposed both upstream and downstream of the electronics in a push-and-pull-through system. Relatively high aerodynamic efficiencies may be achieved with this type of air mover, but unfortunately require high rotational speeds that typically result in unacceptable acoustic levels.
Centrifugal blowers are better suited for the higher pressures encountered in high cooling load applications. However, centrifugal blowers have not typically been considered for electronics chassis cooling, particularly in compact arrangements, due to their relatively larger physical size. As a result, centrifugal blowers have not commonly been considered for fit within cooling system packaging space. For example, a single inlet centrifugal blower sized to match the performance of two axial fans in series can require twice the volumetric space, be less efficient, and result in a less uniform flow field.
It is therefore an object of the present invention to provide a cooling system that simultaneously increases performance and reduces noise of conventional air movers.
It is a further object of the present invention to provide a cooling arrangement that is particularly well suited for cooling densely populated electronic components, such as telecommunication edge routers.